Jb. Ashen et Lj. Goff, MOLECULAR-IDENTIFICATION OF A BACTERIUM ASSOCIATED WITH GALL FORMATION IN THE MARINE RED ALGA PRIONITIS-LANCEOLATA, Journal of phycology, 32(2), 1996, pp. 286-297
The polymerase chain reaction (PCR) was used to amplify eubacterial sm
all-subunit (16S) ribosomal DNA (rDNA) genes from galls of the marine
red alga Prionitis lanceolata Harvey (Gigartinales). These tumors cons
ist of hypertrophied algal cells containing large numbers of intercell
ular bacteria that remain uncultivable. PCR-amplified 16S rDNAs from s
urface-sterilized gall tissue plugs were cloned, sequenced, and analyz
ed by alignment to available small-subunit rRNA sequences (University
of Illinois Ribosomal Database Project). Variable regions were identif
ied and used to construct a fluorescently labeled, species-specific ol
igodeoxynucleotide probe for whole cell in situ hybridization to the g
all symbiont. Probe 949 (PLANC.949) localized the P. lanceolata bacter
ial symbiont in preparations from mature gall tissue. This probe did n
ot hybridize to the rDNA of closely related bacteria included as contr
ols in the same hybridization reactions. In situ hybridization reveale
d the presence of the same bacterium in association with P. lanceolata
gall formation from three central California localities. Distance and
parsimony analyses suggest that this organism is a member of the Prot
eobacteria (alpha subdivision; Rhodobacter group) and is most closely
related to Roseobacter denitrificans.